A non-contact transmission apparatus is known in which power or signals are transmitted among electrical apparatuses without requiring direct connection of the electrical apparatuses through wiring. For example, Patent Literature 1 discloses an electronic circuit element called a “digital isolator.”
This technology enables isolation to be established between the ground of a logic signal and the ground of an RF signal. For example, non-contact transmission technology such as described above is used in a gate driving element such as a semiconductor switching element for power electronics, because the source potential of the semiconductor switching element varies based on a high voltage and thus it is necessary to insulate a direct-current component between the interior of the gate driving element and the power semiconductor switching element.
In transmission and reception of signals between a high-frequency semiconductor chip and an external device, if the transmission line is configured using wire bonding, uncertain parasitic capacitance or inductance that influences the characteristics of high-frequency signals will occur. The non-contact transmission technology as described above is also used in such a case.
As the non-contact transmission technology, electromagnetic resonance couplers (also called “electromagnetic field resonance couplers”) that use the coupling of two electric wiring resonators as disclosed in Patent Literature 2 and Non-Patent Literature 1 have been gathering great attention in recent years. A feature of the electromagnetic resonance couplers is that highly efficient and long-range signal transmission is possible.